File : s-ransee.adb
1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT RUN-TIME COMPONENTS --
4 -- --
5 -- S Y S T E M . R A N D O M _ S E E D --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 2011-2012, Free Software Foundation, Inc. --
10 -- --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. --
17 -- --
18 -- --
19 -- --
20 -- --
21 -- --
22 -- You should have received a copy of the GNU General Public License and --
23 -- a copy of the GCC Runtime Library Exception along with this program; --
24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
25 -- <http://www.gnu.org/licenses/>. --
26 -- --
27 -- GNAT was originally developed by the GNAT team at New York University. --
28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
29 -- --
30 ------------------------------------------------------------------------------
31
32 -- Version used on all systems except Ravenscar where Calendar is unavailable
33
34 with Ada.Calendar; use Ada.Calendar;
35 with Ada.Unchecked_Conversion;
36
37 package body System.Random_Seed is
38
39 Y2K : constant Time :=
40 Time_Of (Year => 2000, Month => 1, Day => 1, Seconds => 0.0);
41 -- First day of Year 2000, to get a duration
42
43 function To_U64 is
44 new Ada.Unchecked_Conversion (Duration, Interfaces.Unsigned_64);
45
46 --------------
47 -- Get_Seed --
48 --------------
49
50 function Get_Seed return Interfaces.Unsigned_64 is
51 begin
52 return To_U64 (Clock - Y2K);
53 end Get_Seed;
54
55 end System.Random_Seed;